Breast cancer is the most common cancer among women other than skin cancer, and is the second leading cause of cancer death in women after lung cancer. The American Cancer Society currently estimates that there are about 182,460 new cases of invasive breast cancer per year among women in the United States and 40,480 deaths per year from the disease. Prevention and early diagnosis of breast cancer are of foremost importance. Because early breast cancer does not produce symptoms, the American Cancer Society recommends an x-ray mammogram screening and a clinical breast examination every year for women over the age of 40. Recently, the American Cancer Society has additionally recommended an adjunctive breast MRI (magnetic resonance imaging) screening for women in certain higher-risk groups. Although the preferred embodiments described hereinbelow are particularly applicable and advantageous for use in x-ray mammography and x-ray tomosynthesis breast cancer screening environments, they are also readily applicable for other breast imaging modalities such as breast MRI, breast computed tomography (CT), and breast ultrasound.
Computer-aided detection (CAD) generally refers to the use of computers to analyze medical images to detect anatomical abnormalities in the subject body part. Sometimes used interchangeably with the term computer-aided detection are the terms computer-aided diagnosis, computer-assisted diagnosis, or computer-assisted detection. Upon acquisition of a digital or digitized medical image, a CAD algorithm processes the medical image to detect locations thereon having sufficient likelihood of being associated with an abnormal condition to qualify as a CAD detection, i.e., to qualify as a location on the image that warrants particular attention by a radiologist (or other suitable medical professional) for closer analysis. The CAD algorithm usually identifies a preliminary set of candidate locations in a medical image and then selects which ones, if any, will qualify as actual CAD detections based on a variety of computed features associated with the candidate detections. The CAD results are most often communicated in the form of annotation maps comprising graphical annotations (CAD markers) overlaid on a diagnostic-quality or reduced-resolution version of the medical image, one CAD marker for each CAD detection.
CAD results are mainly used by radiologists as “secondary reads” or secondary diagnosis tools. When analyzing a medical image, the radiologist usually makes his or her own analytical determinations before looking at the CAD results, which either verify those determinations or trigger further inspection of the image. Some CAD implementations have used CAD results in a “concurrent reading” context in which the radiologists look at the CAD results at the same time that they look at the images.
In the field of x-ray mammography, thousands of x-ray mammography CAD systems are now installed worldwide, and are used to assist radiologists in the interpretation of millions of mammograms per year. X-ray mammography CAD systems are described, for example, in U.S. Pat. No. 5,452,367, U.S. Pat. No. 5,572,565, U.S. Pat. No. 5,729,620, U.S. Pat. No. 5,815,591, U.S. Pat. No. 5,917,929, U.S. Pat. No. 6,075,879, U.S. Pat. No. 6,266,435, U.S. Pat. No. 6,301,378, U.S. Pat. No. 6,434,262, and U.S. Pat. No. 6,901,156, each of which is incorporated by reference herein. X-ray mammography CAD algorithms analyze digital or digitized images of standard mammographic views (e.g. CC, MLO) for characteristics commonly associated with breast cancer, such as calcifications, masses, and architectural distortions. CAD systems for use with other modalities such as breast MRI, breast CT, and breast ultrasound imaging are also in various stages of development, although none yet approaches x-ray mammography in terms of widespread acceptance and adoption.
It would be desirable to provide a CAD system for use in breast cancer screening that provides even better performance in the identification of imaged tissue features that may be indicative of a cancerous condition. It would be further desirable to provide a CAD user interface accommodating such improved functionality. Other issues arise as would be apparent to one skilled in the art upon reading the present disclosure.